This invention relates to a process for the removal of iron from iron-containing petroleum crudes, heavy hydrocarbonaceous residua, or solvent deasphalted oils derived from crudes and residua, using amino-carboxylic acids as sequestering or chelating agents. A few, but increasingly important, petroleum crude feedstocks and residua contain levels of iron which render them difficult, if not impossible, to process using conventional refining techniques. Specifically, the iron contaminants causing particular problems are in the form of non-porphyrin, organometallically-bound compounds. These species have been attributed to either naturally-occurring iron complexes or solubilized iron from the corrosion and decay of iron bearing equipment which comes in contact with crude oils. One possible class of iron-containing compounds identified in particular is the iron naphthenates and their homologous series. These organo-iron compounds are not separated from the feedstock by normal desalting processes, and, if left untreated, they can cause the very rapid deactivation of hydroprocessing catalysts in conventional refining operations. Examples of feedstocks demonstrating objectionably high levels of iron compounds are those from the San Joaquin Valley in Cailfornia. Generally, these crudes are contained in a pipeline mixture referred to as San Joaquin Valley crude or residuum.
The problems presented by iron in petroleum feedstocks, and the necessity for removing it, has been known for some time, but the prior art contains few specific references to particular solutions to its removal. Metals removal generally using organic compounds, however, has been also addressed in the prior art, but specifically for the removal of known metallic contaminants, such as nickel, vanadium, and/or copper, which are also ordinarily found in feedstocks as porphyrins, and other organometallic compounds.
In U.S. Pat. No. 3,052,637, Lerner, metals-contaminants are removed from crude petroleum feedstocks using a 2-pyrrolidone-alcohol mixture. In U.S. Pat. No. 3,167,500, Payne, metallic contaminants, such as metal-containing porphyrins, are removed from petroleum oils using a condensed polynuclear aromatic compound having a preferred C/H ratio and a molecular weight ordinarily called pitch binders. In U.S. Pat. No. 3,153,623, Eldib et al, selected commercially available organic compounds of high dielectric strength were added to assist in the electrically directed precipitation removing metals with the polar organic molecules.
It has now been unexpectedly found that the iron-containing contaminants may be effectively removed from the feedstocks of the present invention by binding the iron compounds using amino-carboxylic acids and their salts.